Elevator table

ABSTRACT

An upper and a parallel lower platform are connected by at least two transversely spaced lever units each having two crossed levers which are pivoted at their point of intersection and whose respective upper and lower ends are provided with rollers guided in guides of the upper and lower platform, respectively. The upper and/or the lower ends of the crossed levers of each unit have associated therewith at least one additional lever one end of which is pivoted to the respective platform intermediate the ends of the levers associated therewith, whereas the other end is pivoted to one of the two levers of the unit intermediate the point of intersection of the levers and the end of the lever which is connected with the respective platform. More of the additional levers can also be provided.

1111 3,823,915 1451 July 16, 1974 I ELEVATOR TABLE Siegfried Koehler,Wiesbaden, Germany [75] Inventor:

[73] Assignee: Trepel AG., Wiesbaden, Germany [22] Filed: Dec. 29, 1972[21] Appl. No.: 319,770

[30] 9 Foreign Application Priority Data Feb. 24, 1972 Germany 2208777521 US. Cl. '254/122 [51] Int. Cl B661 3/22 [58] Field of Search254/122, 124; 187/18 [56] References Cited UNITED STATES PATENTS3,112,676 12/1963 Boulsover 254/122 3,623,707 11/1971 Klopp 254/122FOREIGN PATENTS OR APPLICATIONS 1,080,750 4/1960 Germany 254/122 428,31212/1947 Italy 254/124 Primary Examiner-A1 Lawrence Smith AssistantExaminer-Robert C. Watson Attorney, Agent, or FirmMichael S. Striker 57] ABSTRACT An upper and a parallel lower platform are connected by atleast two transversely spaced lever units each having two crossed leverswhich are pivoted at their point of intersection and whose respectiveupper and lower ends are provided with rollers guided in guides of theupper and lower platform, respectively. The upper and/or the lower endsof the crossed levers of each unit have associated therewith at leastone additional lever one end of which is pivoted to the respectiveplatform intermediate the endsof the levers associated therewith,whereas the other end is pivoted to one of the two levers of the unitintermediate the point of intersection of the levers and the end of thelever which is connected with the respective platform. More of theadditional levers can also be provided.

8 Claims, 1 Drawing Figure 1 ELEVATOR TABLE BACKGROUND OF THE INVENTIONThe present invention relates to a device for raising and loweringloads,and more particularly to an elevator table.

Such tables, operating on the scissors or pantograph principle, arealready known. They use an upper and a lower platform between whichthere are disposed two or more units each having two crossed levers.Where the levers intersect one another they are pivoted together. Thelower ends of the levers are connected with the lower platform forpivoting movement about fixed pivots. The upper ends of the levers areprovided with rollers which can roll in guides provided on the upperplatform. It is also known to reverse the relationship so that therollers are associated with the lower platform and the fixed pivots areassociated with the upper platform.

In these prior-art constructions the center point between the four endsof the two crossed levers of each unit, that is the point ofintersection between these levers, will shift in the direction towardsthat platform with which the lever ends are connected at the fixedpivots, as the upper platform is being raised and will move awaytherefrom as the upper platform is being lowered. This particularmovement is of no consequence if the elevator table raises or lowersloads which are relatively light in weight, or which are notparticularly long. If, however, the loads are long or are rather heavy,this movement of the point of intersection will result in an unevendistribution of the load to the lever arms of the levers, and at timesthis can lead to bending of the levers or even breakage thereof.

Evidently, this is undesirable and severely limits th utility of theelevator tables known from the art.

SUMMARY OF THE INVENTION It is, accordingly, a general object of thepresent invention to overcome the disadvantages of the prior art.

More particularly it is an object of the present invention to provide animproved elevator table of the type under discussion, which is notpossessed of the aforementioned disadvantages.

Still more particularly it is an object of the present invention toprovide such an improved elevator table in which there will be nopreferential shifting of the point of intersection between the crossedlevers towards one or the other of the platforms.

In keeping with these objects, and with others which will becomeapparent hereafter, one feature of the invention resides in an elevatortable which, briefly stated, comprises an upper and a parallel lowerplatplatforms intermediate the lever ends associated with the same, andanother end portion pivoted to one of the levers of the respective unitintermediate the point of intersection and the lever ends which areassociated with this one platform.

With this construction all lever ends are in rolling engagement with therespective platforms, that is none of the lever ends are connected witha platform for movement about fixed pivots. Instead, the fixed pivots,or rather the action thereof,'is replaced in the construction accordingto the present invention by that end of the additional lever which isconnected with the respective platform. This means that when the upperplatform is being raised the lever ends provided with the rollers willshift uniformly towards the center, and the point of intersection willalways be in the same position relative Additional lever meanscomprising at least one additional lever for each unit is also provided,and this additional lever has one end portion pivoted to one of the toboth platforms. As the upper platform is raised, the center of the loadcarried on it, and thepoint of intersection will no longer becomedisplaced relative to one another as was the case in the prior art, andhence the uneven distribution of load to the variouslevers which hasbeen so objectionable in the prior art is overcome.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however,

both as to its construction and its method of operation, together withadditional objects and advantages thereof, will be best understood fromthe following description of specific embodiments when read inconnection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE is a somewhatdiagrammatic il lustration of an exemplary embodiment of the invention.1

DESCRIPTION OF THE PREFERRED EMBODIMENTS comprise pumps, hydrauliccylinders, hydraulic-fluid.

reservoirs and the like, all of which are entirely conventional in thisparticular field.

Also conventional in the illustrated embodiment is the provision of anupper platform 6 and a parallel lower platform 7. The term platform ishere not restricted to any particular structural concept in thiscontext; evidently, the lower platform 7 could be a plate, but it couldalso be a base of any suitable type or configuration. The platform 6usually is plate-shaped.

The two platforms 6 and 7 are-vertically spaced from one another and theelevator table is provided with two transversely spaced lever units 4,of which only one is illustrated, it being understood that the other onewill be located behind it. It is, of course, also conceivable that onlya single lever unit 4 might be utilized.

In the illustrated embodiment the lever units 4 are composed of twocrossed levers 2 each having an upper lever arm 2a and a lower lever arm2b. The levers 2 of each unit 4 are pivoted together at the pivot point3, that is at the point of intersection of the levers 2. The

upper ends of the upper lever arms 2a'are provided with rollers 1 whichare received in guide slots provided in the upper platform 6, and thelower ends of the lower lever arms 2b are similarly provided withrollers 1 which are received in guide slots of the lower platform 7.

Thus far, the construction of theillustrated elevator table isconventional except for the fact that in the prior art only one set ofends (either the upper ends or the lower ends) would be provided withthe rollers 1, whereas the other ends would be connected with therespective platform for movement about fixed pivots rather than onrollers.

There is a further difference in accordance with the present invention,namely the provision of additional lever means. In the illustratedembodiment this additional lever means comprises additional levers 5.Here, the levers are provided in the form of two pair of such levers,associated with the upper and lower platforms, respectively. However, asingle such lever 5 could be associated with each of the upper and lowerplatforms, or a single such lever 5 could be associated with one of theupper and lower platforms, or again a pair of such levers could beassociated with either the platform 6 or the platform 7.

In the. illustrated embodiment, however, there are provided two pair ofthe levers 5, as already mentioned, each associated with one of theplatforms 6 and 7. The levers 5 associated with the lever arms 2a arepivoted to the latter midway between the point of intersection 3 and therespective roller 1, and the opposite end of each lever 5 is pivoted tothe upper platform 6 via a pivot 9. The levers 5 associated with thelever arms 2b are arranged similarly, that is one end of eachlever 5 ispivoted to a respective lever arm 2b intermediate the associated roller1 and the point of intersection 3, whereas the opposite end of the samelever-5 is pivoted withthe pivot 9 to the lower platform 7. The locationof the pivots 9 is midway between the ends of the lever arms 2a, or 2b,respectively.

In the illustrated embodiment there is provided mounting means for thepivots 9, here shown as guides 8 which so mount the pivots 9 that thesame can move toward and away from the point of intersection 3 by alimited extent. Such an arrangement has the advantage that it prevents,if heavy or very heavy loads are carried on the platform 6, damage tothe levers 2 and 5 if a downward deformation of the platform 6 shouldresult vided in form of a fluid-operated cylinder and piston I unit 10which is connected with the platform 6 and with the pivot 9,respectively. The cylinder and piston unit is advantageously a hydraulicunit. However, other means for effecting the displacement can also beutilized. The necessary fluid lines and fluid supply means for the unit10 have been omitted for the sake of clarlty.

If the levers 5 are connected fixedly with the platform 6 (or 7) butpivotable in the general plane of the levers 2, then the platform 6 (or7) receives a further supporting point which means that it can be madeless massive and less strong (especially if it is of large dimension)than would otherwise be necessary if there were only two supportingpoints (rollers 1 at the endsof the associated lever arms). lf unit 4 isprovided with only a single or a pair of the levers 5, then it isadvantageous if these act between the levers 2 and the platform 6,rather than between the platform 7 and the levers 2. Of course, bothplatforms and levers can be so provided.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types'described above.

While the invention has been illustrated and described as embodied inanelevator table, it is not intended to be limited to the details shown,since various modifications and structural changes may be made withoutdeparting in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range-of equivalence of thefollowing claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. An elevator table, comprising an upper and a parallel lower platform;at least one lever unit intermediate said platforms and comprising twocrossed levers pivoted together at their point of intersection andhaving respective upper ends associated with said upper platform, andlower ends associated with said lower platform; rollers provided on saidupper ends in rolling engagement with said upper platform, and on saidlower ends in rolling engagement with said lower platform; additionallever means comprising additional levers, each of said additional levershaving one end portion located at one of said platforms intermediate thelever ends associated therewith, and another end portion pivoted to oneof the levers intermediate said point of intersection and the lever endsassociated with said one platform; pivot means pivoting said one endportion to said one platform; and mounting means mounting said pivotmeans for movement substantially parallel to the plane of said platformrelative to the latter.

2. An elevator table as defined in claim 1, wherein said mounting meanscomprises guide means engaging said pivot means for movement of the samesubstantially normal to the plane of said platform.

3. An elevator table as defined in claim 1, wherein said one platform issaid upper platform.

4. An elevator table as defined in claim 1, wherein said one platform issaid lower platform.

5. An elevator table as defined in claim l,'wherein said additionallever is pivotable in the general plane of said crossed levers.

6. An elevator table as defined in claim 1; further comprising pivotmeans pivoting said one end portion to said one platform; and mountingmeans mounting 6 said pivot means for movement in at least substantialmovement of the same. parallelism with the plane of said one platformand in An elevator table as defined in claimq, wherein the general planeof said crossed levers.

7. An elevator table as defined in claim 6; and further I I comprisingfluid-operated cylinder-and-piston means 5 cylmderand'plston associatedwith said pivot means for effecting said said cylinder-and-piston meanscomprises a hydraulic

1. An elevator table, comprising an upper and a parallel lower platform;at least one lever unit intermediate said platforms and comprising twocrossed levers pivoted together at their point of intersection andhaving respective upper ends associated with said upper platform, andlower ends associated with said lower platform; rollers provided on saidupper ends in rolling engagement with said upper platform, and on saidlower ends in rolling engagement with said lower platform; additionallever means comprising additional levers, each of said additional levershaving one end portion located at one of said platforms intermediate thelever ends associated therewith, and another end portion pivoted to oneof the levers intermediate said point of intersection and the lever endsassociated with said one platform; pivot means pivoting said one endportion to said one platform; and mounting means mounting said pivotmeans for movement substantially parallel to the plane of said platformrelative to the latter.
 2. An elevator table as defined in claim 1,wherein said mounting means comprises guide means engaging said pivotmeans for movement of the same substantially normal to the plane of saidplatform.
 3. An elevator table as defined in claim 1, wherein said oneplatform is said upper platform.
 4. An elevator table as defined inclaim 1, wherein said one platform is said lower platform.
 5. Anelevator table as defined in claim 1, wherein said additional lever ispivotable in the general plane of said crossed levers.
 6. An elevatortable as defined in claim 1; further comprising pivot means pivotingsaid one end portion to said one platform; and mounting means mountingsaid pivot means for movement in at least substantial parallelism withthe plane of said one platform and in the general plane of said crossedlevers.
 7. An elevator table as defined in claim 6; and furthercomprising fluid-operated cylinder-and-piston means associated with saidpivot means for effecting said movement of the same.
 8. An elevatortable as defined in claim 7, wherein said cylinder-and-piston meanscomprises a hydraulic cylinder-and-piston unit.